1. Field of the Invention
Various embodiments relate to a semiconductor memory device, a memory system having the same, and a method of operating the same.
2. Discussion of Related Art
Semiconductor memory devices are storage devices that are typically implemented using a semiconductor, such as for example silicon (Si), germanium (Ge), a gallium arsenide (GaAs), indium phosphrous (InP), or the like. Semiconductor memory devices are often classified as either a volatile memory device or a non-volatile memory device.
A volatile memory device is a memory device that retains stored data as long as power is supplied to the volatile memory device. Stored data is lost when power to a volatile memory device is interrupted. Examples of volatile memory devices include, but are not limited to, a static random access memory (SRAM), a dynamic random access memory (DRAM), and a synchronous DRAM (SDRAM). A non-volatile memory is a memory device that retains stored even when power supplied to the non-volatile memory device is interrupted. Examples of a non-volatile memory device include, but are not limited to, a read-only memory (ROM), a programmable ROM (PROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a flash memory, a phase-change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), and a ferroelectric RAM (FRAM). Flash memories may be classified as one of a NOR-type flash memory and a NAND-type flash memory.
Flash memories are typically configured as either a two-dimensional semiconductor device where a plurality of strings are horizontally formed on a semiconductor substrate and a three-dimensional semiconductor device where a plurality of strings are vertically formed on the substrate.
Each of the plurality of strings includes a drain select transistor, memory cells, and a source select transistor that are electrically coupled in series between a bit line and a source line.